1. Field of the Invention
The present invention relates to a moisture measuring device for measuring a moisture (H.sub.2 O) concentration in a measuring gas by taking a difference between an oxygen concentration based solely on the oxygen partial pressure in the measuring gas and an oxygen concentration including the oxygen partial pressure obtained by an electrolysis of the moisture (H.sub.2 O) in the measuring gas.
2. Related Art Statement
Moisture measuring devices for measuring moisture concentration or water content in a measuring gas consisting of a base gas including oxygen and vaporized water by using an oxygen concentration detecting device formed of a solid electrolyte member are known, for instance, from that disclosed in Japanese patent application laid opened number 60-105,957. This moisture measuring device disclosed in the abovementioned patent specification comprises a gas storing chamber provided with a small hole for introducing the measuring gas including moisture and oxygen, a solid electrolyte type oxygen concentration detector so arranged in the gas storing chamber that the measuring electrodes come in contact with the measuring gas introduced in the gas storing chamber, and a standard gas supplying mechanism which removes the measuring gas from the gas storing chamber and supplies the measuring gas to a comparing electrode portion of the oxygen concentration detector. The standard gas supplying mechanism comprises a standard gas extracting tube, a dehumidifier for removing moisture from the measuring gas taken out by the extracting tube, and a pump for transporting the measuring gas through the extracting tube. The dehumidifier is connected directly to the gas outlet of the gas extracting tube or connected to the gas outlet through a coupling tube heated by a heater or the like and the moisture concentration or water content in the measuring gas is measured by using an oxygen concentration detector.
In such a known moisture measuring device, however, as the measuring gas is once introduced into a dehumidifier outside a furnace by a pump and a reference gas is obtained, the construction of the device inevitably becomes complicated and bulky. Furthermore, essentially there is unavoidable measuring error based on the time difference between the measuring gas directly introduced to the location of the measuring electrodes and the dehumidified gas introduced into the location of comparing electrodes in the oxygen concentration detector after dehumidification. This measuring error can not be removed even suppressing the variation of the oxygen concentration by taking the average of the variation. Also as the measuring gas is dried in the dehumidifier, the response time of the overall system becomes longer at least by the time required for the drying.